The use of radiation to treat medical conditions comprises a known area of prior art endeavor. For example, radiation therapy comprises an important component of many treatment plans for reducing or eliminating unwanted tumors. Unfortunately, applied radiation does not inherently discriminate between unwanted structures and adjacent tissues, organs, or the like that are desired or even critical to continued survival of the patient. As a result, radiation is ordinarily applied in a carefully administered manner to at least attempt to restrict the radiation to a given target volume.
That said, however, there are numerous challenges to administering radiation doses as intended. The radiation-treatment application setting, for example, typically comprises a physically-dynamic setting. In particular, a given radiation-treatment session will typically span at least many minutes and various scene components can move during that time.
Some of these movements can be predictable, at least to an extent. The patient, for example, can be expected to breathe periodically during the treatment course and this can cause various organs and tissues to move with respiration. Many other types of movement can occur, however. For example, an expected periodic movement (such as a respiration-based movement) can vary unexpected with respect to its periodicity (and hence experience a drift in movement phase) and/or its amplitude. Yet other types of movement can be random (as when, for example, the patient sneezes) and have no discernable relationship to a periodic or otherwise expected movement.
Unfortunately, existing approaches to attempt to compensate for movement during radiation treatment are not fully satisfactory for all application settings.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.